[3] In 1926, she began to work as voluntary help in the Curie laboratory at the Institut du radium, under Langevin's recommendations, then as a free worker the next year.

Montel stayed with him until he died, in 1946, visiting him while he was under house arrest in Troyes during World War II.

She published Langevin's last work, which was realised during World War II when he was in house arrest, on "The device could manage to study the nature of ions and follow its formation and evolution, giving the mobility spectrum".

[10] In the following years, she taught physics and chemistry in high school in Fontainebleau, near Paris, until her retirement in the 1960s.

In 1972, she worked on Langevin's 100th birthday commemoration, publishing texts in his memory in some periodicals and writing a personal text, Langevin et le rationalisme, le savant hors de la tour d'ivoire to be published in Scientia.